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The Pirate Bay gave no warning to users before running a 'test' that embedded JavaScript to run a cryptocurrency miner that hogged CPU resources.

For once, the Motion Picture Association of America (MPAA) and Recording Industry Association of America(RIAA) might have been tickled by the famous piracy site The Pirate Bay after the site ticked off some pirates by hijacking their CPU cycles to secretly mine cryptocurrency.

Apparently ads to generate revenue and bitcoin donations weren’t cutting it, so The Pirate Bay decided to run a test without any warning to users. JavaScript code was added that “borrowed” visitors’ CPU cycles in order to mine for the cryptocurrency Monero.

While the code for the miner was not embedded on every page, visitors browsing categories or search results experienced huge spikes in CPU usage. A user on Reddit claimed all CPU threads jumped to 100 percent, later modifying that claim to 80 to 85 percent.

It didn’t take long for users to spot the code in the site’s footer. The Pirate Bay added JavaScript from Coinhive, which is described as “a crypto miner for your website.”

Torrent Freak reported, “The miner does indeed appear to increase CPU usage quite a bit. It is throttled at different rates (we’ve seen both 0.6 and 0.8) but the increase in resources is immediately noticeable.”

Even the Coinhive JavaScript Miner documentation notes, “While it’s possible to run the miner without informing your users, we strongly advise against it. You know this. Long-term goodwill of your users is much more important than any short-term profits.”

Blocking the JavaScript code running on The Pirate Bay

The nasty backlash about The Pirate Bay trying this without any warning was not limited to unhappy users. As “Sid,” a PirateBay forum administrator and supermod, noted, “That really is serious, so hopefully we can get some action on it quickly.”

About an hour later, Sid suggested using NoScript to block the JavaScript-based crypto-miner from running until the code was removed from The Pirate Bay. Other users in social media added that add-ons like ScriptBlock or ScriptSafe also blocked the code, or JavaScript could be disabled in browser settings.

While there were several variations of the following amusing Reddit comment, “How dare they steal my CPU resources to pay for stolen movies!” — it’s not necessarily true. For anyone thinking The Pirate Bay is only used by people trying to bypass paying for copyrighted material, keep in mind that not all visitors are pirates. Torrents, or magnets, are often used as a way to distribute legitimate free software.

Eventually, The Pirate Bay told Torrent Freak that the miner was being tested for about 24 hours “as a new way to generate revenue” and “could eventually replace the ads on the site.”

If The Pirate Bay or any other site were to replace ads with an automatic miner, users should definitely be notified beforehand. Eighty to 100 percent spikes when sitting idle on a page would make a computer pretty sluggish. Some people might be cool with ditching ads in exchange for some CPU resources, but that's doubtful if it comes at a cost of a computer being turned into molasses.